environments Krotection
Agency
Offict of ^etticid* Progum* (TS-766C)
Wjjhington. OC 20400
5<«C/FS- 92-221
v^EPA Pesticide
Fact Sheet
Name of Chemical:
Reason for Issuance:
Date Issued:
Pseudomonas fluorescens and
Pseudomonas syringae strains
Registration of New Biological Pesticide
September l6. 1992
238
Fact Sheet Number:
DESCRIPTION OF CHEMICAL
Generic Name: Pseudomonas fluorescens A506
Pseudomonas fluorescens 1629RS
Pseudomonas svrinaae 742RS
Trade Name: Frostban
EPA Shaughnessy Codes: 006418 and 006411
Year of Initial Registration: 1992
Pesticide Type: Biological Control Agent
U.S. and Foreign Producers: Frost Technology Corporation
USE PATTERNS AND FORMULATIONS
APPLICATION SITES: Application will be made to cherry, apple,
pear, almond and peach trees and tomato, potato and strawberry
plants.
METHOD OF APPLICATION: Application may be made using standard
ground spray equipment for applying dilute or concentrate sprays.
TYPE OF FORMULATION: Products are powder formulations containing
11.3 x 10 colony forming units (CFU)/gram. This is equivalent to
71% of each isolate alone in three products or a total of 71% from
a combination of the three isolates in another product.
APPLICATION RATES: The products are applied at the rate of
0.33 lbs/acre for concentrate sprays or 0.44 lbs/acre for dilute
sprays.
SCIENCE FINDINGS
Summary Science Statement
The results of the data submitted confirm the lack of
mammalian toxicity or pathogenicity of the live strains of the
bacteria in the Frostban products by oral or inhalation routes of
exposure, by intraperitoneal injection or by dermal application.

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Requests for waivers of data requirements for avian oral,
freshwater fish, freshwater aquatic invertebrate and nontarget
insect testing were granted. Nontarget plant testing indicated
that the strains of Pseudomonas in these products did not have any
adverse effects on the plants tested. Testing of the organisms on
honey bees was not submitted. Since the products will be applied
during flowering, the honey bee testing will be required as a
condition of registration. The organisms in these products will
not pose a risk to wild mammalian species or to any endangered
species.
Data for environmental fate are not triggered under current
requirements for these products since the organisms are naturally
occurring species and the results of initial Tier I tests did not
indicate the need for additional testing.
CHEMICAL CHARACTERISTICS
Physical/Chemical Properties
Color:
Physical State:
Odor;
Bulk Density:
pH:
Corrosivity:
Storage Stability:
Light tan
Powder
fish
0.4g/cc
6.7
Non-corrosive
Unstable unless kept cool
<4
»10°C)
Toxicoloaica1 Characteristics
Acute oral toxicity/pathogenicity test: Results of this test
indicated that the combined organisms in these products were not
toxic or pathogenic to rats ? days after exposure to a dosage of
8.4 x 10 CFU.
Acute intraperitoneal injection test: The test material was not
lethal to or significantly toxic#to mice when injected in a single
intraperitoneal dose of 2.8 x 10 CFU/animal.
Additional data/information: Testing of various Pseudomonas
strains closely related to those contained in these products were
conducted. Acute oral and acute inhalation toxicity tests
indicated that the strains tested were not lethal or toxic to rats.
Primary eye and primary dermal studies in rabbits using closely
related organisms showed no significant irritation effects.
Ecological Characteristics
No adverse effects are expected from the use of these products
on avian wildlife, aquatic organisms or nontarget insects because
of the lack of demonstrated toxicity of the bacteria on these types
of organisms. Additionally, due to the natural occurrence and

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ubiquitous nature of the organisms and their lack of persistence on
the crop plant, these products are not expected to cause a
significant impact on these organisms.
In the nontarget plant study which was submitted, no adverse
effects on the nontarget plants in the test were demonstrated.
No adverse effects to mammalian systems would be expected
because of the lack of toxicity demonstrated in the toxicity
testing of the Pseudomonas strains.
Ho risk to endangered species is expected due to the low
toxicity, natural occurrence, ubiquitous nature, lack of
phytotoxicity and lack of persistence of the bacteria.
Due to the application of the products during plant flowering,
when honey bees are most active, a honey bee test is being required
as a condition of registration.
BENEFITS
Some bacteria, which are found naturally on plant surfaces,
initiate frost formation by providing a nucleus for ice formation.
When such bacteria are present on plant surfaces, frost damage
occurs at higher temperatures than when they are absent. The
bacteria in these products, when applied to newly emerging plant
tissue will displace the ice-nucleating bacteria which might
normally occupy that site. Since these bacteria do not initiate
ice-nucleation, the plant can withstand temperatures several
degrees less before being affected by frost. This temperature
difference would often be sufficient to prevent loss of the crop
due to damaging effects of frost on flowers or tender foliage in
the spring or may extend the growing season in the fall.
Ice-nucleating bacteria may also be controlled by chemical
means. Registration of a biological frost prevention agent would
provide a safer alternative to chemical pesticides.
The products are also intended to be used in an integrated
fire blight control program on apples and pears. The products will
be used in combination with reduced rates of standard antibiotic
products currently used for fire blight control. This type of
program would reduce exposure to antibiotics and possibly reduce or
delay development of antibiotic resistance in humans and animals.
TOLERANCE ASSESSMENT
The petition which was submitted requested a generic exemption
for the bacterial species Pseudomonas fluorescens and Pseudomonas
syringae. It was concluded that there are insufficient data to
support an exemption from tolerance requirements for all strains of
these very common and widespread bacteria at this time. The data

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are adequate to support an exemption from tolerance requirements
for the specific bacterial strains in these products.
An exemption from the requirement of a tolerance is
established for the residues of Pseudomonas fluorescens strain
A506, Pseudomonas fluorescens strain 1629RS, and Pseudomonas
svrinqae strain 742RS in or on all raw agricultural commodities
when applied as a frost preventive or biological control agent on
growing agricultural crops in accordance with good agricultural
practices. Based upon the lack of toxicity and pathogenicity of
these organisms in the Tier I mammalian toxicity/pathogenicity
studies, an exemption from tolerance requirements is warranted.
Additionally, data were submitted to demonstrate that there is a
significant population of naturally occurring fluorescent
pseudomonads present on washed fresh produce intended to be
consumed raw.
SUMMARY OF MAJOR DATA GAPS
The only outstanding data gap for this biological control
agent is the requirement for conducting a study to determine the
effects of these organisms on honey bees. The study is being
required since the products will be applied at flowering when bees
are most active. There have been no reports of toxicity to insects
caused by these bacteria so the risk posed to honey bees by
conditional registration would be minimal. Additionally, the time
limit being imposed for completion of this test (9 months) would
insure that the study is completed prior to the spring use season
for the products. Therefore, a conditional registration would be
justified.
CONTACT PERSON AT EPA
Susan T. Lewis,
Product Manager (PM) 21,
Registration Division (H—7505C),
Environmental Protection Agency,
401 M Street, SW,
Washington, D.C. 20460
Office location and telephone number:
Rm. 227, CM/2
1921 Jefferson Davis Highway,
Arlington, VA 22202.
(703) 305-6900.
DISCLAIMER: The information in this Pesticide Fact Sheet is a
summary only and is not to be used to satisfy data requirements for
pesticide registration and reregistration.

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